Automatic reel hub assembly

ABSTRACT

An automatic reel hub assembly which is easily manufactured and assembled includes an axially movable central shaft, a generally cylindrical support member having a central axial aperture receiving the central shaft, a plurality of shoes mounted on the support member in a circumferentially dispersed relationship for only radial motion with respect thereto, and a plurality of drive links, each providing a pin-free coupling between a different shoe and the central shaft. Apertures within the shoes and the shaft receive opposite ends of the drive links in mating relationships which permit the drive links to translate axial shaft motion into radial shoe motion. A circumferentially extending groove in the outer circumference of the support member and the outer surfaces of the shoes receives a recessed elastic O-ring band which exerts a radially inward force on each shoe without subjecting the band to wear as reels are loaded and unloaded.

' United States Patent Urynowicz Dec. 2, 1975 l l AUTOMATIC REEL HUBASSEMBLY [75] Inventor: James P. Urynowicz, Los An eles, [57] ABSTRACTI' g Ca An automatic reel hub assembly which is easily manul Assigfleimp P RCdWOOd Ci y, factured and assembled includes an axially movablelif central shaft, a generally cylindrical support member [22] Filed:May 15, 1974 having a central axial aperture receiving the centralshaft, a plurality of shoes mounted on the support [2]] Appl. No.:470,127 member in a circumferentially dispersed relationship for onlyradial motion with respect thereto, and a plu- [52] us. CL" 242/683;242/72 rality of drive links, each providing a pin-free coupling [51]Int Cl 2 B65 17/02 between a different shoe and the central shaft. Aper-[58] Field of Search 242/683, 68.1, 68.2, 72, "5? 2"? E f s, j z

242/721, 461 4647 210; 92/89, 92 105 en s o t e rive in s in mating reations ips w .lC

permit the drive links to translate axial shaft motion [561 Cited llliifl 3f? QKZFZZELZEZLZZ???lli iilli fi UNITED STATES PATENTS member andthe outer surfaces of the shoes receives a 3,3l3,496 4/1967 Northrup242/683 recessed elastic O-ring band which exerts a 31366343 l/lgfsMessamer a] 242/683 inward force on each shoe without subjecting theband 2:2 :2 21] to wear as reels are loaded and unloaded.

Primary ExaminerLeonard D. Christian 23 Claims, 13 Drawing Figures IU.S. Patent Deci2, 1975 Shet1of4 3,923,268

US. Patent Dec. 2, 1975 Sheet 2 of4 3,923,268

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- g W 2/ Z QM ON J AUTOMATIC REEL HUB ASSEMBLY BACKGROUND OF THEINVENTION 1. Field of the Invention This invention relates to reel hubassemblies and more particularly to reel hub assemblies for digitalmagnetic tape transports which automatically lock a reel in itsoperating position after it has been manually placed on the hub.

2. History of the Prior Art A magnetic tape transport typically includesa pair of spaced apart reel hubs supporting a removable supply reel anda take-up reel. As the tape transport is operated, tape is passedbi-directionally from the supply reel past tape buffers, magnetic heads,and a drive capstan to a take-up reel. Because of the frequent need toremove one supply reel and replace it with a different supply reel it isdesirable that the supply reel hub readily permit the loading andremoval of reels of tape. A standard tape reel has a smooth, circular,axially extending-central aperture which receives a reel hub as the tapereel is loaded. After a reel is in place the reel hub must be capable ofexpanding to engage the inner circumference of the central reel aperturein a non-sliding relationship.

One generally known automatic reel hub assembly includes a central shaftand a pneumatic actuator for selectively moving the shaft axiallybetween releasing and engagement positions. The circumference of theshaft is provided with a conical surface which engages the matingconical surfaces of a plurality of radially extendable collet definingsegments which are dispersed about the shaft to define the hubcircumference. The collet segments are moved radially outward or inwardas the shaft moves axially toward the engagement and release positionsrespectively. An elastic band about the outer circumference of thecollet segments provides structural integrity for the assembly as itbiases the segments radially inward and provides a high coefficient offriction element which engages the interior circumference of a reel oftape. However, a complicated pinning arrangement which makes the hubassembly expensive to manufacture and assemble is required to permittorque to be transmitted from a reel motor and through the shaft to thecollet. This pinning arrangement must permit the collet segments to moveradially while they are closely constrained to a circumference definingconfiguration and rotational torque is transmitted thereto. Theresulting arrangement is relatively complex and contributessubstantially to the manufacturing and assembly costs of the hubassemblies. Furthermore, the circumferential band is subject to wear andpresents a high frictional surface which often imposes a drag tointerfere with the loading and removal of tape reels.

SUMMARY OF THE INVENTION An easily assembled automatic reel hub assemblyin accordance with the invention includes an axially movable shaft, apneumatic or other actuator connected to selectively position the shaftat alternate reel engagement and release positions, a generallycylindrical support member having a central axial aperture whichreceives the shaft, a plurality of circumferentially dispersed shoesmounted on the support member for only radial motion with respectthereto, a recessed, circumferential elastic band encompassing thesupport member to bias the shoes radially inward and a plurality ofdrive links. Each drive link is a small generally radially extending barwhich couples a different shoe to the shaft through pin-free connectionsof first and second opposite ends having curved shapes which matinglyengage a shoe and the shaft respectively in a manner permitting axialmotion of the shaft to be translated to radial motion of the engagedshoe. This arrangement is very easily assembled, does not require acomplicated pinning configuration in order to transmit torque from thecentral shaft through the shoes to a loaded tape reel, and does notrequire sliding engagement between two mating conical surfaces.Furthermore, outer surfaces of the shoes may be coated with a highcoefficient of friction material such as neoprene, raybestos or rubberfor non-slip engagement with the interior circumference of a tape reelaperture. Undesirable contact between the high coefficient of frictionsurfaces and the interior circumference of a tape reel is avoided as thetape reel is loaded or unloaded by recession of these shoe surfacesbelow the outer circumference of the support member. Because the supportmember defines the majority of the hub circumference, this recession ofthe shoes does not seriously affect the structural continuity of the hubsurface. Recession of the circumferential elastic O-ring band incircumferential grooves protects the band from wear as tape reels areloaded and removed.

BRIEF DESCRIPTION OF THE DRAWINGS A better understanding of theinvention may be had from a consideration of the following detaileddescription taken in conjunction with the accompanying drawings inwhich:

FIG. 1 is a perspective view, partly broken away, of an automatic reelhub assembly in accordance with the invention;

FIG. 2 is a sectioned front view of the automatic reel hub assemblytaken along the lines 2-2 in the direction of the arrows as indicated inFIG. 1;

FIG. 3 is an end view taken from the rear of a support member used inthe reel hub assembly shown in FIG. 1;

FIG. 4 is a section view of the support member taken along the line 4-4in the direction of the arrows as shown in FIG. 3;

FIG. 5 is an end view taken from the front of a support member collarfor the hub assembly shown in FIGS. 1 and 2;

FIG. 6 is a sectioned side view of the support member collar taken alongthe lines 6-6 in the direction of the arrows as shown in FIG. 5;

FIG. 7 is a fragmentary end in view, taken from the rear and partlybroken away, of a hub portion of the support member collar shown inFIGS. 5 and 6;

FIG. 8 is a side view of a drive link used in the reel hub assemblyshown in FIGS. 1 and 2;

FIG. 9 is a top view of the drive link shown in FIG. 8;

FIG. 10 is a plan view of a shoe used in the reel hub assembly shown inFIGS. 1 and 2;

FIG. 11 is an end view of the shoe shown in FIG. 10;

FIG. 12 is a plan view of a shaft used in the reel hub assembly shown inFIGS. 1 and 2; and

FIG. 13 is an end view of the shaft shown in FIG. 12 taken from therear.

DETAILED DESCRIPTION As shown in FIGS. 1 and 2, an automatic reel hubassembly 10 in accordance with the invention is concentricallypositioned about a central axis 12 and includes a conventional reelmotor 14 mechanically linked to a hub 16 through a multipart hollowshaft 18. The hub 16 includes a generally cylindrical collar 20 whichhas a disk shaped anterior support wall-22 and which is rotatablymounted on an anteriorly extending portion of a reel motor drive shaft24. A generally cylindrical support member 26 is fastened in matingrelationship to the forward side of the anterior supportwall 22 ofcollar 20 by three bolts 28 which are dispersed about the central axis12 at angles of 120 from one another. To-

gether, the support member 26 and collar 20 define three radiallyextending and circumferentially distributed apertures 30 for receivingshoes 32. The apertures 30 are axially coextensive with a rearwardcylindrical portion 34 of the support member 26. A reel 38 having a tapepack 36 also has an axial thickness which is coextensive withcylindrical portion 34 when a rearward surface 42 of the reel 38 is inabutment with an anterior surface 44 of a flange 46 which extendsradially outward from the anterior support wall 22 to provide a backstopfor loaded reels. A slightly conical anterior circumferential surface 48of support member 26 is tapered radially inward as it extends forwardfrom cylindrical surface 34 to guide tape reels onto the hub 16. Aspring loaded cylindrical plunger 50 is positioned to extend radiallythrough the rearward portion of conical surface 48 diametricallyopposite each shoe 32 to provide a detent as reels 38 are loaded andunloaded. A screw 52 protrudes from the plunger 50. The forward portionof hub 16 is defined by a cap 56 having the shape of a truncated conewith a disk shaped anterior wall 58 and a conical outer circumferentialsurface 60 extending from the anterior wall 58 to the conical surface 48in alignment therewith. An O-ring 62 is recessed within acircumferential groove 64 in surface 34 of support member 26 and matinggrooves 66 in the shoes 32. The O-ring 62 biases the shoes radiallyinward.

A pneumatic actuator 68 is coupled to radially position the shoes 32 inresponse to pneumatic pressures generated by a pressure control system70. The pneumatic actuator includes a diaphragm 72 connected between thecap 56 and the support member 26 along the mating periphery thereof toform a generally cylindrical pressure chamber 74 between the diaphragm72 and cap 56. A generally disk shaped piston 76 is disposed to supportthe diaphragm 72 axially rearward of the chamber 74. The piston 76 has acentral aperture 78 which is concentric with the axis 12. A threadedscrew 80 having a central axial bore 82 therethrough passes through ahole 84 in the diaphragm corresponding to the central aperture 78 inpiston 76 and then through aperture 78 to threadingly engage the forwardend of an actuator shaft 86 which has an axial central bore 88communicating with bore 82 and which forms the forward portion of hollowshaft 18. The actuator shaft 86 extends slidingly through the supportmember 26 and the collar 20 with the rearward end being slidinglyreceived by a central axial bore 94 in motor shaft 24. A diametric bore96 near the rearward extremity of actuator shaft 86 provides pneumaticcommunication between the axial bore 94 and the outer circumference ofactuator shaft 86. A rear tip 98 of reduced outer diameter is formed onthe actuator shaft 86 from a point in front of the diametric bore 96 tothe rearward extremity of the actuator shaft 86 to provide pneumaticcommunication from the diametric bore 96 to the rear- 4 ward extremity.A pushrod 100 of somewhat smaller diameter than the axial bore 94extending through hollow reel motor shaft 24 has a forward threaded endwhich mates with a tapped rearward end of actuator shaft 86. Theopposite rearward end of pushrod 100 extends rearward beyond reel motorshaft 24.

The pushrod 100 terminates at the rearward end in a small diameter tipportion 102 which extends beyond the rearwardmost extremity of the reelmotor shaft 24. Support for the rearward end 102 of pushrod 100 isprovided by a spring housing 104. The spring housing 104 is a generallycylindrical member having an inside diameter substantially equal to theinside diameter of reel motor shaft 24 having aperture 106 through arear wall 108 thereof and an open end through which the rearward end ofthe pushrod 100 is extended in supporting relationship. At the forwardend the spring housing 104 receives the rearward end of the motor shaft24 in mating relationship and a pair of set screws 110 (only one shown)which are positioned 90 apart are threaded radially through thecylindrical wall of spring housing 104 to engage slots 112 in the outercircumference of motor shaft 24 near the rear thereof to secure thespring housing 104 to the motor shaft 24. A

washer 114 having a central hole approximately equal in diameter to thesmall diameter end 102 of pushrod 100 receives the small diameter end102 and is disposed at thetransition from the small diameter end 102 tothe larger diameter main portion of pushrod 100. A coil spring 56 isdisposed between the rearward surface of washer 54 and the insidesurface of the closed end 108 of spring housing 104 to bias the pushrod100 in a forward direction until the forwardmost surface of washer 54makes contact with the rearwardmost end of reel motor shaft 24. Thisforwardmost position is indicated by dashed lines 116 in FIG. 2 andrepresents a reel release position. A C-clamp 118 is received by acircumferential groove near the rearwardmost end of pushrod 100. TheC-clamp 118 is positioned rearward of the closed end of spring housing104 and limits axial movement of pushrod 100 for ease of assembly orrepair at times when such movement is not otherwise limited byengagement of washer 114 with the rearwardmost end of reel motor shaft24.

A plurality of small holes in the washer 114 are dispersed about thecentral hole which receives the rear tip 102 of pushrod 100 to permitpneumatic communication between the interior of spring housing 104 andthe space between the outer circumference of pushrod 100 and theinterior circumference of reel motor shaft 24 even when the washer 114is in contact with the rearwardmost portion of reel motor shaft 24. Fourair holes 120 which are circumferentially positioned at 90 from oneanother extend through the outer circumference of spring housing 104 topermit pneumatic communication between the interior of spring housing104 and an interior chamber 122 of a bell housing 124 within which thespring housing 104 resides. The generally cylindrical, non-rotating bellhousing 124 provides a pneumatic seal around the spring housing 104 andpushrod 100 which rotate with the reel motor shaft 24. The bell housing124 has a rearward closed end and a forward open end which is closed byabutment with the rearwardmost portion of reel motor 12. A gasket 126maintains the airtight seal between the rearwardmost portion of reelmotor 12 and a radially extending flange of hell housing 124 which ismechanically connected to the reel motor 12 by four bolts 128 which arespaced around the flange at 90 from one another. A threaded fitting 130is screwed into a tapped aperture 132 in the outer periphery of bellhousing 124 and is connected through suitable tubing 134 to an airpressure control system 136. The air pressure control system 136operates under control of signals provided by an associated tapetransport system (not shown) to selectively provide a positive airpressure through the fitting 130 during normal tape transport operation.The air passes through a tube 134 and fitting 130 to the interiorchamber 122 of bell housing 124, and then through apertures 120 to theinterior of spring housing 104.

With the pushrod 100 biased to an axially forward or reel releaseposition by a spring 138 disposed concentrically about the rear tip 102of pushrod 100 between the washer 114 and spring housing rear wall 108,the pressurized air travels through the small holes in washer 114 andthen along the space between the inner circumference of hollow reelmotor shaft 24 and the outer circumference of pushrod 100 from therearwardmost portion of reel motor shaft 24 to the forwardmost portionof reel motor shaft 24. Near the forwardmost portion of reel motor shaft24 the pressurized air travels through apertures 96 to the interior ofactuator shaft 86 and then forward through the central axial bore inbolt 84 to the chamber 74. As the pressurized air enters the chamber 74a rearwardly directed force is applied to diaphragm 72 and piston 76until the piston 76, actuator shaft 86, and pushrod 100 are drivenrearward against the bias of spring 138. The actuator mechanism isdriven rearward until either engagement of the shoes 32 with a reel 38prevents further motion or a rearwardly projecting peripheral flange onpiston 38 engages a forward mating surface of support housing 16. Thisis the position in which the automatic reel hub assembly is depicted inFIG. 2. A circumferential groove 140 in actuator shaft 86 receives oneend of each of three drive links 142 which have their opposite endengaged by the three shoes 32 and which translate axial motion of theactuator shaft 86 into radial motion of the shoes 32. Axial motion ofthe actuator shaft 86 orients the drive links 142 more nearlyperpendicular to central axis 12 to drive the opposite ends and coupledshoes 32 radially outward. The total travel distance between therearwardmost reel engaged position and forwardmost reel release positionof the axially moving portions of the automatic reel hub assembly 10 isapproximately 0.375 inch. Because the air leakage of the pneumaticactuator is very small, the actuator provides very little air or powerdrain on the air pressure control system 136 while an associated tapetransport is in operation.

The three detent plungers 50 are generally elongated cylinders having aspherical closed end and an opposite bored end which receives a coilspring 143. The coil spring 143 extends from the bored end of theplunger 50 to push against the bottom of a radially extending bore inthe support member 26 to bias the plunger radially outward. An axiallydirected hole 54 in the support member provides communication betweenthe radially directed plunger hole and the rear of the support member26. This axially directed hole 54 permits a stop member such as a rollpin or the set screw 52 to be inserted into a bore in the sidewall ofthe plunger 50. The stop member extends beyond the plunger circumferenceto engage the most radially outward portion of the inside surface ofaccess bore 54 to limit the radially outward travel of plunger 50. As areel is inserted over the hub 10, it must contact the spherical closedends of the three detent plungers 50, causing them to be moved radiallyinward against the force of the springs 84 as the reel is loaded. Thethree detent plungers 50 are axially positioned such that therearwardmost portion of the plungers 50 engage the forward edge of aloaded reel 38. The plungers 50 thus provide a detent for maintaining areel 38 in the proper axial position prior to engagement thereof by theshoes 32.

As shown in further detail in FIGS. 3 and 4 the support member 26 is agenerally cylindrical, integrally constructed element which ispositioned concentrically about the central axis 12. A forward surface144 of the support member 26 is formed concave inward, that is axiallyrearward, and receives the piston 76 and diaphragm 72. Surface 144defines a relatively flat, disk shaped anterior wall within the outercircumference of the support member but may be radiused at the peripherythereof. The forward edge of the relatively conical circumference 48terminates in a flat anterior surface 146 lying in a plane which isperpendicular to the central axis 12 and defines the forwardmost portionof support member 26.

At the rear of the support member 26 a very large diameter bore 148extends axially forward for a short distance to define a rearwardlyextending, relatively thin circumferential wall 150 and a planarinterior rear wall 152. A medium sized bore 154 extends from the rearwall 152 axially forward to the rear surface 156 of a relatively thinwall 158 having the forward surface thereof defined by surface 144. Asmall central bore 160 extends through the wall 158 between surfaces 156and 144 with a diameter slightly larger than the diameter of the largediameter forward end of actuator shaft 86. Diametrically opposite eachof three cylindrical bores 162 for receiving detent plungers 50, arectangular shoe aperture 164 extends radially outward from the mediumsized bore 154 to the outer circumference of the support member 34. Thethree shoe apertures 164 have a uniform cross section perpendicular toradially extending directions and guide the shoe 32 as they moveradially between radially extended reel engagement and radially inwardreel release positions. A small shoe restraint bore 166 extends axiallyforward a short distance into the front wall of each of the three shoeapertures 164. The bores 166 receive a roll pin 168 which extends fromthe forward edge of each shoe 32. The bore 166 and roll pins 168 limitthe radial travel of the three shoes 32. Inasmuch as the bores 166 andpins 168 do not participate in the normal operation of the hub assembly10 by the transmission of torque or otherwise, dimensional tolerancesare not critical. They merely serve to facilitate assembly and tocontain the shoes in the event the O-ring 62 should break.

Six uniformly spaced countersunk holes 170 extend forward from theinterior rear wall 152 through the forward surface 146 of conicalcircumferential wall 40 to receive screws 172 (only one shown) formechanically coupling the support member 26 to cap 56 and diaphragm 72.Three tapped holes 172 in the interior rear wall 152 of support member26 are spaced radially inward from the holes 170 and receive bolts 28(see FIG. 2) which mechanically fasten the rearward portion of thesupport member 26 to a forward facing portion of the collar 20 in matingrelationship.

Collar 20 is shown in further detail in FIGS. 5, 6 and 7 to whichfurther reference is now made. Collar 20 comprises a disk or flangeportion 176 at the anterior end and a cylindrical hub portion 178positioned rearward of the disk or flange portion 176. A rectangularcross section circumferential notch 180 defining a forward facing planarsurface 182 and a short forward projecting tongue 184 which is receivedby the large diameter bore 148 of the support member 26 in matingrelationship. The tongue 184 is bored axially rearward to the plane ofsurface 182 with an intermediate size hole 186 which matches mediumsized bore 154 of support member 26. Three radially extending slots 188are also formed in the tongue 184 to an axial depth which is coextensivewith the plane of surface 182. These slots 188 are sized and positionedto match the three shoe receiving apertures 164 of support member 26. Asmall bore 190 for receiving an intermediate sized central portion ofthe actuator shaft 86 extends from the plane of surface 182 axiallyrearward part way into the hub portion 178 concentric with the centralaxis 12.

As best shown in FIG. 7 a narrow diametrically extending slot 192extends from a planar, rearwardmost surface 194 of hub portion 178axially forward to approximately the axial midpoint 196 of hub portion178. A motor shaft bore 202 which is concentric with central axis 12extends forward from rear surface 194 beyond the extent of slot 192. Themotor shaft bore 202 receives the forward portion of reel motor shaft 24in mating relationship and slot 192 permits the hub portion 178 ofcollar to be tightly clamped about reel motor shaft 24 by oppositelyoriented bolts 204, 206 which extend through the hub portion 178 ofcollar 20 perpendicular to slot 192. A pair of bolt notches 208, 210 arecut into the periphery of hub portion 178 to provide planar surfaces212, 214 against which the heads of bolts 204, 206 may rest. Bolt holes216, 218 receive the bolts 204, 206 and are tapped throughout a portionof the hub portion 176 which lies on the opposite side of slot 192 fromthe surfaces 212, 214.

As representatively shown in greater detail in FIGS. 8 and 9, the threeidentical drive links 142 are each generally rectangular bars havingoppositely facing broad surfaces 224, oppositely facing side surfaces226 which are somewhat narrower than broad surfaces 224 and ends 228,230. The ends 228, 230 are radiused with respect to axes extendingparallel to broad surfaces 224 to form smoothly curved surfaces whichmay be matingly received by the grooves 140 and shoes 32. Each drivelink 142 has dimensions of 1.505 inches in length between theextremities of the rounded ends, a width of approximately 0.310 inchacross the broad surfaces 224, and a depth of approximately 0.15 inchacross side surfaces 226 (between broad surfaces 224). The radiused ends228, 230 permit the drive link 142 to rotate within drive link receivingapertures within the shoes 32 and groove 140 of actuator shaft 86 as thedrive links convert axial motion of shaft 86 to radial motion of theshoes 32.

One of the three identical shoes 32 is representatively illustrated ingreater detail in FIGS. 10 and 11. The shoes 32 are generallyrectangular in shape with opposing broad walls 234, 236, opposing endwalls 238, 240, a top 242, and a bottom 244. A slot 246 having interiorside walls 248, 250 extends between the two ends 238, 240 upwardly fromthe bottom 244 to a notched anterior surface having a portion 252adjacent end 238 which is spaced from top 242 a greater distance than asurface portion 254 adjacent end 240. The displacement of surfaceportion 252 from portion 254 defines a notch which permits a small bore256 to extend inward a short distance from end 238. Each bore 256receives a roll pin 258 which extends beyond end surface 238 to engagean aperture 54 in support member 26 to limit the radial travel of theshoes 32. A small bore 260 extends through each shoe 32 along a centralaxis which extends perpendicular to broad faces 234, 236 approximatelythrough the plane of surface 254 to form a circular trough or groovewhich receives a first end 228 of a drive link 142 in matingrelationship. The bore 260 has a radius slightly larger-than the radiusof the radiused end 228 of drive link 142. When biased radially inwardagainst the end 228 of drive link 142, the interior portion of bore 260mates with the end 228 to limit relative movement between the drive link142 and shoe 32 in non-radial directions. The interior side wallsurfaces 248, 250 adjoin the side walls 226 of drive link 142 to limitsideways motion of a drive link 142 relative to a mating shoe. The end228 of a drive link 142 is then permitted to rotate about the axis ofbore 260 within the trough defined by bore 260. So long as shoe 32 isradially biased into engagement with the first end 228 of drive link142, other relative motion between the shoe 32 and drive link 142 is notpermitted. As an alternative to the bore 260, the shoes 32 may be moldedwith a trough defined in the interior surface 254 which is approximatelycoextensive with the trough which is defined therein by bore 260. Bymolding the shoes 32 with the trough already present therein, amanufacturing step of boring the hole 260 may be avoided, thus makingthe manufacturing process easier.

An axially extending slot 262 which extends between end surfaces 238,240 is formed in the top 242 of the shoes 32 to receive pads 264 of ahigh coefficient of friction material such as rubber, neoprene orraybestos. The pads 264 engage the interior surfaces of the hubs ofloaded reels when the shoes 32 are extended to grip the reel in anon-slip relationship. A circumferential slot 66 is formed through thepad 264 and top 242 at a location between the ends 238, 240 to permitalignment with slot 64 in support member 26 to receive an O-ring 62which extends around the circumference of support member 26 and shoes 32to bias the shoes 32 radially inward. The slots 64, 66 permit the O-ring62 to be recessed below the periphery of the reel hub assembly 10 toprevent contact with tape reels as they are loaded and removed from thehub assembly 10. The resilient O-ring 62 thus permits a radial bias tobe applied to the shoes 32 without O-ring 62 being subject to wear andtear as reels are loaded and unloaded. Furthermore, reels 38 need not besubject to accidental engagement with the O-ring 62 which wouldinterfere with loading and unloading.

As shown in further detail in FIGS. 12 and 13, the actuator shaft 86 isa generally cylindrically shaped member having a large diameter forwardend 274, a medium diameter central portion 276 and a small diameterrearward portion 278. A front planar surface 280 defines the forwardmostportion of shaft 86 and a planar surface 282 defines the rearwardmostportion of shaft 86. The shaft 86 has a length of approximately 2.72inches between the two ends 280, 282 and a diameter of approximately0.60 inch at the large diameter forward portion 274. The medium diametercentral portion 276 begins 1.1 1 inches from end 280 and has a diameterof 0.355 inch. The small diameter rearward portion 278 begins 2.04inches from end 280 and has a diameter of 0.280 inch. A central axialbore 288 extends longitudinally between the two ends 280, 282 with adiameter of approximately O.l59 inch. A tapped forward bore 290 extendspart way into the shaft 86 from forward end 280 to receive bolt 80 whichfastens the diaphragm 72 and piston 76 to actuator shaft 86. At therearward end of shaft 86 a tapped axial bore 292 is provided to receivethe threaded front end of pushrod 100. A diametrically extending throughhole 296 having diameter of 0.l4 inch is disposed between theforwardmost portion of tapped bore 292 and the transition of smalldiameter rear portion 278 to medium diameter central portion 276 toprovide communication between the outer circumference of small diameterportion 278 and the longitudinal central bore 288.

The circumferential groove 140 is formed in the large diameter portion274 of shaft 86 symmetrically about a plane which lies perpendicular tocentral axis 12 at 0.74 inch from forward end 280. The groove 140 has acircular radially inward or smaller diameter portion 296 having a radiusof 0.093 inch and a smallest diameter about central axis 12 of 0.25inch. Forward side walls 298 and rearward side walls 300 are generallylinear in cross section and extend tangentially from circular bottomportion 296 to the outer circumference of enlarged diameter portion 274.The side walls 298, 300 intersect a plane 302 which is perpendicular tothe central axis 12 at an angle of approximately 40.

The curved groove 140 receives the second end 230 of the three drivelinks 142 in a mating relationship which permits the second end 230 torotate within groove 140 as the actuator shaft 86 moves axially inresponse to actuator 68. The mating relationship between groove 140 andsecond end 230 prohibits relative axial motion between the three drivelinks 142 and the groove 140.

Tape reels are loaded and unloaded by directing air pressure controlsystem 136 to release the positive pressure which drives the pneumaticactuator 68. Release of this positive pressure permits spring 138 todrive pushrod 100, actuator shaft 86, and piston 76 axially forward to arelease position 116. In this released position 116, the angle of thethree drive links 142 is slightly increased with respect to a plane 302lying perpendicular to the central axis 12. The increase of this angledecreases the radial distance of the three shoes 32 from the centralaxis 12, permitting disengagement of the three pads 264 from theinterior surface of a hub of a reel 38 so that the reel 38 may beremoved and replaced with a new reel. A new reel is loaded by pushing atpast detent plungers 50 until the rear surface of the new reel engagesthe planar surface 182 near the periphery of collar 20. Once the newreel is loaded, air pressure control system 136 again creates a positivepressure which is directed into chamber 74 to apply a force againstpiston 76 and drive the shaft 86, and pushrod 100 axially rearward.Because of the good mechanical advantage provided by the drive linkcoupling arrangement, the area of the piston and the small frictionalforces which are encountered, a positive pressure of 2 PSI has beenfound to be adequate. The rearward motion of the actuator shaft 86forces the three drive links 142 to a more nearly perpendicularorientation, causing them to force the three shoes 32 radially outwarduntil the three pads 264 firmly grip the interior surface of the hub ofthe new reel. At this point the new reel is loaded and tape transportoperation may begin.

Although there has been shown and described a particular embodiment ofan automatic reel hub assembly in accordance with the invention, for thepurpose of enabling a person of ordinary skill in the art to make anduse the invention, it will be appreciated that the invention is notlimited thereto. Accordingly all modifications, variations andequivalent arrangements within the scope of the appended claims shouldbe considered to be within the scope of the invention.

What is claimed is:

1. A reel hub assembly comprising:

an actuator shaft which is axially movable relative to a radiallydisposed shoe between a reel lock position and a reel release position,the actuator shaft being adapted at one axial position therealong toreceive at least one drive link end in a mating relationship whichprevents axial motion of the shaft relative to a mated end of a drivelink while permitting radial motion of an end opposite the mated end ofa drive link with respect to the shaft;

at least one drive link having opposed ends disposed to extend generallyradially with respect to the actuator shaft with one end in a matingrelationship with the actuator shaft at the one axial position and anopposite end in a mating relationship with a shoe, both said one andopposite end mating relationships permitting radial motion of the drivelink relative to the mate while preventing axial motion of the drivelink relative to the mate;

at least one shoe adapted to receive an opposite end of a drive link ina mating relationship which permits radial but not axial motion of saidopposite end relative to the shoe; and

an actuator mechanism connected to cause relative axial motion of theshoe and actuator shaft between a reel lock axial position relationshipand a reel release axial position relationship to move the shoe betweena radially extended position and a radially retracted positionrespectively.

2. The reel hub assembly as set forth in claim 1 above, wherein thedrive link limits the radial proximity of the shoe to the shaft andfurther comprising a resilient element disposed to radially bias theshoe toward the shaft.

3. The reel hub assembly as set forth in claim 2 above, furthercomprising a housing having a central axially extending aperturereceiving the actuator shaft and a plurality of radially extendingapertures, each receiving a different shoe and associated drive link.

4. The reel hub assembly as set forth in claim 3 above, furthercomprising a thin layer of material having a high coefficient offriction affixed to the most radially outward surfaces of the shoes.

5. The reel hub assembly as set forth in claim 3 above, wherein theactuator includes a second resilient element connected to axially biasthe actuator shaft toward the reel release position relative to theshoes.

6. The reel hub assembly as set forth in claim 5 above, wherein theactuator further includes a chamber connected to the housing, thechamber being partly defined by a diaphragm which is coupled to theactuator shaft and which is axially movable in response to fluidpressure within the chamber, and a fluid pressure source coupled toselectively increase the fluid pressure within the chamber to force theactuator shaft to the reel lock position and decrease the pressurewithin the chamber to permit movement of the actuator shaft to the reelrelease position.

7. An automatic reel hub assembly comprising:

a generally cylindrical body member having a central axial aperture forreceiving a central shaft and having a plurality of radially extendingshoe apertures providing communication between the central axialaperture and an outer circumference of the body member, each radiallyextending aperture being adapted to receive a shoe;

a plurality of shoes, each being disposed for radial motion within adifferent shoe aperture, each having an outer surface adapted forgripping engagement with an interior surface of a reel hub, and eachhaving an inner surface opposite the outer surface which has a concavitytherein, the concavity being adopted to limit nonradial relative motionbetween the shoe and an end of a drive link received within theconcavity;

a central shaft disposed for axial motion within the central aperture,the shaft having a concavity for receiving an end of a drive link whichis adapted to limit relative axial motion between the central shaft anda drive link end disposed approximately opposite each shoe concavity;

a plurality of drive links extending between a shoe concavity and anopposite central shaft concavity, each drive link having a first endadapted for mating engagement with a shoe concavity and a second endadapted for mating engagement with a central shaft concavity;

means for biasing each shoe radially inward; and

means for controlling the axial position of the central shaft relativeto the body member.

8. The hub assembly as set forth in claim 7 above, wherein the concavityin each shoe is adapted to permit an engaged drive link to rotatethrough at least a small are about an axis positioned near the first endthereof which is perpendicular to a plane extending through a centralaxis of the body member and an approximate center point of a concavityand to prevent an engaged drive link from rotating about an axis whichis positioned near the first end thereof generally parallel to a centralaxis of the housing.

9. The hub assembly as set forth in claim 7 above, wherein each shoecomprises a generally rectangular housing having a top, a bottomopposite the top, opposite first and second sides and ends, a slotextending between the two ends and from the bottom to a planar interiorsurface disposed partway between the top and bottom, and a cylindricalconcavity having a central axis lying approximately in the plane of theinner surface perpendicular to the side walls.

10. The hub assembly as set forth in claim 7 above, wherein the drivelink comprises a long generally rectangular bar having first and secondopposing ends and opposing pairs of side walls and end walls, the firstand second ends being rounded about axes of curvature which areperpendicular to the side walls.

11. The hub assembly as set forth in claim 7 above, wherein the centralshaft comprises a hollow, axially extending shaft having a singlecircumferentially extending groove in the outer circumference thereofdefining drive link end receiving central shaft concavity.

12. The hub assembly as set forth in claim 11 above, wherein the centralshaft groove has a cross sectional shape in a plane passing through acentral axis of the shaft of a circular are defining the deepest portionof the groove and straight lines extending tangentially from theextremities of the arc to the outer circumference of the shaft.

13. The hub assembly as set forth in claim 12 above, wherein the arcsubtends an angle of approximately about its center.

14. A reel hub assembly comprising:

a plurality of shoes disposed about a central axis, the shoes havingradially outward surfaces which are suitable for engagement with a reel,being disposed to move radially outward to engage a reel and moveradially inward to release a reel, and having cavities which openradially inward and are adapted for pin-free engagement and retention offirst ends of a drive link as drive link ends which are located radiallyinward from the first ends are moved axially at a fixed radial distancefrom the central axis to control the radial position of the shoes;

a plurality of drive links, each having a first end in pin-freeengagement with a cavity of a different shoe and a second end disposedradially inward with respect to the first end; and i a drive mechanismadapted for pin-free engagement and retention of the second drive linkends, the drive mechanism providing selected axial motion for the seconddrive link ends while maintaining the radial distance of the seconddrive link ends from the central axis substantially constant.

15. An easily assembled reel hub assembly comprising an axially movableshaft, a generally cylindrical support member having an axiallyextending central aperture and receiving the shaft therethrough, aplurality of shoes having radially outward surfaces adapted forengagement with a reel of tape supported by the support member in amanner permitting only radial movement of the shoes, and means forexerting a force on each shoe which is directed radially inward and aplurality of drive links, each coupling a different shoe to the shaftthrough pin-free connections of first and second opposite ends whichengage a shoe and the shaft respectively such that axial motion of theshaft is translated to radial motion of the shoes.

16. For use in a tape transport, a tape reel hub assembly comprising:

a shaft having a central axis and a periphery with at least one cavitytherein, the shaft being translationally movable along the axis andconnectable for rotation about the axis by a motor;

means for translationally positioning the shaft while maintaining aplurality of shoes in a fixed axial position;

a plurality of drive links, each having a first curved end in matingrelationship with a cavity in the shaft and a second curved end oppositethe first curved end; and

a plurality of shoes, each having an outer surface suitable for matingrelationship with a tape reel and an inner surface with a cavity thereinreceiving a second curved end of a drive link in a pin-free matingrelationship in which the second curved end engages the cavity.

17. A reel hub assembly comprising:

an axially extending actuator shaft disposed for axial positioning, theactuator shaft having at least one concavity in the circumferencethereof which is shaped to receive at least one drive link in matingrelationship, the actuator shaft further having a central aperturetherein which extends axially from one end to a position past the atleast one concavity;

an axially flxed wall defining a portion of a chamber which is disposedat said one end of the actuator shaft in communication with the centralaperture thereof;

an axially movable wall which defines a portion of the chamber and whichis coupled to the actuator shaft, the movable wall and actuator shaftbeing axially movable in response to fluid pressure in the chamber toaxially position the at least one concavy;

at least one shoe which is mounted for radial motion with respect to theactuator shaft;

at least one drive link disposed between a shoe and a concavity in theactuator shaft to radially position a shoe in response to an axialposition of the actuator shaft; and

means for biasing the at least one shoe radially inward.

18. The reel hub assembly according to claim 17 above, furthercomprising a reel motor having a hollow motor shaft coupled in axialalignment with the actuator shaft with the actuator shaft being axiallymovable with respect to the motor shaft, the motor shaft extendingthrough the reel motor and providing communication between the centralaperture in the actuator shaft and a side of the reel motor opposite thechamber.

19. The reel hub assembly according to claim 18 above, furthercomprising a bell housing fixed to the reel motor on a side opposite thechamber, the bell housing providing a fluid seal about the end of themotor shaft and having an interior which is in communication with asource of pressurized fluid.

20. The reel hub assembly according to claim 19 above, furthercomprising means coupled to the reel motor shaft on a side of the reelmotor opposite the chamber for continuously biasing the actuator shaftaxially toward the chamber with respect to the reel motor shaft.

21. The reel hub assembly according to claim 17 above, furthercomprising a cylindrical collar which is connected to transmitrotational torque between a reel motor shaft and the at least one shoe.

22. The reel hub assembly according to claim 17 above, furthercomprising a flexible diaphragm disposed within the chamber to provide anon-sliding seal 14 between the fixed wall and the movable wall of thechamber.

23. A reel hub assembly comprising:

a reel motor having a motor shaft having a central axis and a centralaperture extending axially therethrough;

a generally cylindrical support member disposed concentrically about thecentral axis, the support member being adapted to receive and support aplurality of shoes and permit only radial motion of the shoes withrespect thereto, being connected in fixed relationship with the motorshaft, and having a central aperture extending therethrough forreceiving an actuator shaft;

a plurality of shoes, each being supported by the support member foronly radial motion with respect thereto;

an actuator shaft disposed within the central aperture of the supportmember and adapted for axial motion with respect to the support member,the actuator shaft having at least one concavity in the circumferencethereof for receiving a plurality of drive links in mating relationshipand having a central bore extending axially therethrough from a forwardend rearwardly past the at least one concavy;

a plurality of drive links, each extending between a shoe and aconcavity in the actuator shaft to impart radial motion to a shoe inresponse to axial motion of the actuator shaft;

a fixed wall disposed in fixed relationship with the support memberforward of the forward end of the actuator shaft to partially define achamber which is in communication with the axial bore in the actuatorshaft at the forward end thereof;

a movable wall connected to the forward end of the actuator shaft, themovable wall forming a part of the chamber and being operable to axiallyposition the actuator shaft in response to fluid pressure in thechamber; and

means for defining a fluid path which couples a rearward end of theaxial bore through the actuator shaft to a source of fluid having acontrolled pressure.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PatentNo.3,923,268 Dated December 2, 1975 Inventofls) James P. Urvnowicz Page 1of It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 3, line 17, after "pack", "36" should read --40--; line 30,between and the period insert --through an axially extending bore 54-.Column 4, line 13, after 'the", "inside" should read -outside-; line 14,after "24" and before "aperture", "having" should read --and havingan--; line 15, after "thereof" and before "through", delete 'and an openend"; line 20, after "apart", insert --and--; line 30, after "spring","56" should read --115-; line 31, after "washer", "54" should read--l14--; line 34, after "washer", "54" should read --ll4--; line 64,after "motor" and before the period "12" should read --14--; line 66,after "motor", "12" should read --l4--; line 68, after "motor", "12"should read --l4--. Column 5, line 5, after "system" (both occurrences)"136" should read line 14, after "spring", "138" should read --1l5--;line 26, "bolt 84" should read --screw line 30, after "spring", "138"should read line 33, after "piston", "38' should read --76-; line 34,after "support" and before "housing", insert --member or--; line 35,'16" should read -26--; line 51, after "system", "136" should read -70--Column 6, line 3, after "springs", "84" should read --143--; line 39,after "member" and before the period "34" should read --26--; line 41,after "the" and before "32", "shoe" should read --shoes--; line 57,after "146" and before "conical", "of" should read --adjacent--; line57, after "wall", "40" Q should read --48--; line 60, after "holes","172" should read --l74--. Column 7, line 3, after "defining" UNITEDSTATES PATENT OFFICE CERTIFICATE OF CCRREC'HCN Patam No. 3,923,268 DatmiDecember 2. 1975 lnvawo hfl James P. Urvnowicz Page 2 of h It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

should read --defines--; line 4, "182" should read --44-@; line 8, "182"should read =44 line 12, "182" should read =44--; line 17, "182" shouldread =-44=-3 line 19, after "in" and before "7", "Fig." should readFigs. 6 and-. Column 8, line 68, after "bore", "288" should read -88-.Column 9, line 8, after "hole", "296" should read --96--; line 14, after"bore", "288" should read --88--; line 27, after "angle" and before"of", insert line 39, after "spring", "138" should read--ll-; line 50,before "past", "at" should read --it-; line 51 after "surface", "182"should read --44--; line 53, after 'system", "136" should read Columnll, line 14, after "being", "adopted" should read -adapted--; line 61,after "fining" and before "drive", insert --a--.

IN THE DRAWINGS: Sheet 2, Fig 2, reference numeral on pin 258 shouldread --l58--; insert reference numeral 166 identifying bore within whichpin 158 resides; insert reference numeral 78 to identify the axial borethrough piston 76; move lead line for reference numeral 84 to identifythe bore through diaphragm 72; insert reference numeral 82 to identifythe bore through screw insert lead line connecting reference numeral 86to actuator shaft; insert lead line connecting reference numeral tocircumferential groove in actuator shaft 86; insert lead line connectingreference numeral 143 to spring which engages pin 50; insert referencenumeral 88 to identify central bore through actuator shaft 86; insertlead line connecting reference numeral 44 to left=hand UNITED STATESPATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 923, 268 DatedDecember 2 1915 Inventor(s) James P Urynowicz Page 3 of It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

side of flange 46 near lower left corner of drawing; insert referencenumeral 112 identifying slot within which set screw 110 resides; insertreference numeral 115 identifying spring within spring housing 108;insert reference numeral 106 identifying aperture through spring housing108 which receives axially extending shaft 100; insert reference numeral124 identifying bell housing; reference numeral 136 should read 70--.Sheet 3, Fig. 3, insert lead line connecting reference numeral 160 tosmall diameter central bore; insert reference numeral 166 identifyinguntapped bore within slot 164 (all three occurrences); insert referencenumeral 174 identifying tapped bore which is radially inward fromcounter sunk bore 170 (all three occurrences) Sheet 3, Fig. 4, definesmall axially extending bore 166 similar to bore 166 in Fig. 2 andstrike cross hatching therein; extend lead line for reference numeral144 to vertically extending surface. Sheet 3, Fig. 6, reference numeral182 should read --44--; insert reference numeral 46 connected by leadline to righthand side of flange opposite surface 44; insert referencenumeral 22 connected by lead line between vertically extending surfacebetween numerals 20 and 176; insert reference numeral 192 identifyingslot in hub of collar 20; insert reference numeral 194 identifying rearsurface of hub of collar 20. Sheet 3, Fig. 7, insert reference numeral192 identifying slot; insert reference numeral 194 identifying rearsurface.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,923,268 Dated December 2 1975 Inventor(s) James P. Urynowicz g it of AIt is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Sheet 4, Fig. 10, insert reference numeral 262 identifying slot which isshown by a broken line. Sheet 4, Fig. 11, inse rt reference numeral 262identifying the slot; insert reference numeral 246 connected by an arrowto identify slot in bottom of shoe 32; insert reference numeral 248identifying left side of slot 246; insert reference numeral 250identifying right side of slot 246; insert reference numeral 32identifying shoe. Sheet 4, Fig. 12, connect reference numeral 274 tolarge diameter portion of actuator shaft 86; reference numeral 288should read -88--;

reference numeral 296 should read --96.

Signed and Scaled this Twenty-sixth D3) of October 1976 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN Q Alluring Officer Commissioner ofPatenrsand Trademarks

1. A reel hub assembly comprising: an actuator shaft which is axiallymovable relative to a radially disposed shoe between a reel lockposition and a reel release position, the actuator shaft being adaptedat one axial position therealong to receive at least one drive link endin a mating relationship which prevents axial motion of the shaftrelative to a mated end of a drive link while permitting radial motionof an end opposite the mated end of a drive link with respect to theshaft; at least one drive link having opposed ends disposed to extendgenerally radially with respect to the actuator shaft with one end in amating relationship with the actuator shaft at the one axial positionand an opposite end in a mating relationship with a shoe, both said oneand opposite end mating relationships permitting radial motion of thedrive link relative to the mate while preventing axial motion of thedrive link relative to the mate; at least one shoe adapted to receive anopposite end of a drive link in a mating relationship which permitsradial but not axial motion of said opposite end relative to the shoe;and an actuator mechanism connected to cause relative axial motion ofthe shoe and actuator shaft between a reel lock axial positionrelationship and a reel release axial position relationship to move theshoe between a radially extended position and a radially retractedposition respectively.
 2. The reel hub assembly as set forth in claim 1above, wherein the drive link limits the radial proximity of the shoe tothe shaft and further comprising a resilient element disposed toradially bias the shoe toward the shaft.
 3. The reel hub assembly as setforth in claim 2 above, further comprising a housing having a centralaxially extending aperture receiving the actuator shaft and a pluralityof radially extending apertures, each receiving a different shoe andassociated drive link.
 4. The reel hub assembly as set forth in claim 3above, further comprising a thin layer of material having a highcoefficient of friction affixed to the most radially outward surfaces ofthe shoes.
 5. The reel hub assembly as set forth in claim 3 above,wherein the actuator includes a second resilient element connected toaxially bias the actuator shafT toward the reel release positionrelative to the shoes.
 6. The reel hub assembly as set forth in claim 5above, wherein the actuator further includes a chamber connected to thehousing, the chamber being partly defined by a diaphragm which iscoupled to the actuator shaft and which is axially movable in responseto fluid pressure within the chamber, and a fluid pressure sourcecoupled to selectively increase the fluid pressure within the chamber toforce the actuator shaft to the reel lock position and decrease thepressure within the chamber to permit movement of the actuator shaft tothe reel release position.
 7. An automatic reel hub assembly comprising:a generally cylindrical body member having a central axial aperture forreceiving a central shaft and having a plurality of radially extendingshoe apertures providing communication between the central axialaperture and an outer circumference of the body member, each radiallyextending aperture being adapted to receive a shoe; a plurality ofshoes, each being disposed for radial motion within a different shoeaperture, each having an outer surface adapted for gripping engagementwith an interior surface of a reel hub, and each having an inner surfaceopposite the outer surface which has a concavity therein, the concavitybeing adopted to limit nonradial relative motion between the shoe and anend of a drive link received within the concavity; a central shaftdisposed for axial motion within the central aperture, the shaft havinga concavity for receiving an end of a drive link which is adapted tolimit relative axial motion between the central shaft and a drive linkend disposed approximately opposite each shoe concavity; a plurality ofdrive links extending between a shoe concavity and an opposite centralshaft concavity, each drive link having a first end adapted for matingengagement with a shoe concavity and a second end adapted for matingengagement with a central shaft concavity; means for biasing each shoeradially inward; and means for controlling the axial position of thecentral shaft relative to the body member.
 8. The hub assembly as setforth in claim 7 above, wherein the concavity in each shoe is adapted topermit an engaged drive link to rotate through at least a small arcabout an axis positioned near the first end thereof which isperpendicular to a plane extending through a central axis of the bodymember and an approximate center point of a concavity and to prevent anengaged drive link from rotating about an axis which is positioned nearthe first end thereof generally parallel to a central axis of thehousing.
 9. The hub assembly as set forth in claim 7 above, wherein eachshoe comprises a generally rectangular housing having a top, a bottomopposite the top, opposite first and second sides and ends, a slotextending between the two ends and from the bottom to a planar interiorsurface disposed partway between the top and bottom, and a cylindricalconcavity having a central axis lying approximately in the plane of theinner surface perpendicular to the side walls.
 10. The hub assembly asset forth in claim 7 above, wherein the drive link comprises a longgenerally rectangular bar having first and second opposing ends andopposing pairs of side walls and end walls, the first and second endsbeing rounded about axes of curvature which are perpendicular to theside walls.
 11. The hub assembly as set forth in claim 7 above, whereinthe central shaft comprises a hollow, axially extending shaft having asingle circumferentially extending groove in the outer circumferencethereof defining drive link end receiving central shaft concavity. 12.The hub assembly as set forth in claim 11 above, wherein the centralshaft groove has a cross sectional shape in a plane passing through acentral axis of the shaft of a circular arc defining the deepest portionof the groove and straight lines extending tangentially from theextremities of the arc to the outer circumFerence of the shaft.
 13. Thehub assembly as set forth in claim 12 above, wherein the arc subtends anangle of approximately 80* about its center.
 14. A reel hub assemblycomprising: a plurality of shoes disposed about a central axis, theshoes having radially outward surfaces which are suitable for engagementwith a reel, being disposed to move radially outward to engage a reeland move radially inward to release a reel, and having cavities whichopen radially inward and are adapted for pin-free engagement andretention of first ends of a drive link as drive link ends which arelocated radially inward from the first ends are moved axially at a fixedradial distance from the central axis to control the radial position ofthe shoes; a plurality of drive links, each having a first end inpin-free engagement with a cavity of a different shoe and a second enddisposed radially inward with respect to the first end; and a drivemechanism adapted for pin-free engagement and retention of the seconddrive link ends, the drive mechanism providing selected axial motion forthe second drive link ends while maintaining the radial distance of thesecond drive link ends from the central axis substantially constant. 15.An easily assembled reel hub assembly comprising an axially movableshaft, a generally cylindrical support member having an axiallyextending central aperture and receiving the shaft therethrough, aplurality of shoes having radially outward surfaces adapted forengagement with a reel of tape supported by the support member in amanner permitting only radial movement of the shoes, and means forexerting a force on each shoe which is directed radially inward and aplurality of drive links, each coupling a different shoe to the shaftthrough pin-free connections of first and second opposite ends whichengage a shoe and the shaft respectively such that axial motion of theshaft is translated to radial motion of the shoes.
 16. For use in a tapetransport, a tape reel hub assembly comprising: a shaft having a centralaxis and a periphery with at least one cavity therein, the shaft beingtranslationally movable along the axis and connectable for rotationabout the axis by a motor; means for translationally positioning theshaft while maintaining a plurality of shoes in a fixed axial position;a plurality of drive links, each having a first curved end in matingrelationship with a cavity in the shaft and a second curved end oppositethe first curved end; and a plurality of shoes, each having an outersurface suitable for mating relationship with a tape reel and an innersurface with a cavity therein receiving a second curved end of a drivelink in a pin-free mating relationship in which the second curved endengages the cavity.
 17. A reel hub assembly comprising: an axiallyextending actuator shaft disposed for axial positioning, the actuatorshaft having at least one concavity in the circumference thereof whichis shaped to receive at least one drive link in mating relationship, theactuator shaft further having a central aperture therein which extendsaxially from one end to a position past the at least one concavity; anaxially fixed wall defining a portion of a chamber which is disposed atsaid one end of the actuator shaft in communication with the centralaperture thereof; an axially movable wall which defines a portion of thechamber and which is coupled to the actuator shaft, the movable wall andactuator shaft being axially movable in response to fluid pressure inthe chamber to axially position the at least one concavity; at least oneshoe which is mounted for radial motion with respect to the actuatorshaft; at least one drive link disposed between a shoe and a concavityin the actuator shaft to radially position a shoe in response to anaxial position of the actuator shaft; and means for biasing the at leastone shoe radially inward.
 18. The reel hub assembly accOrding to claim17 above, further comprising a reel motor having a hollow motor shaftcoupled in axial alignment with the actuator shaft with the actuatorshaft being axially movable with respect to the motor shaft, the motorshaft extending through the reel motor and providing communicationbetween the central aperture in the actuator shaft and a side of thereel motor opposite the chamber.
 19. The reel hub assembly according toclaim 18 above, further comprising a bell housing fixed to the reelmotor on a side opposite the chamber, the bell housing providing a fluidseal about the end of the motor shaft and having an interior which is incommunication with a source of pressurized fluid.
 20. The reel hubassembly according to claim 19 above, further comprising means coupledto the reel motor shaft on a side of the reel motor opposite the chamberfor continuously biasing the actuator shaft axially toward the chamberwith respect to the reel motor shaft.
 21. The reel hub assemblyaccording to claim 17 above, further comprising a cylindrical collarwhich is connected to transmit rotational torque between a reel motorshaft and the at least one shoe.
 22. The reel hub assembly according toclaim 17 above, further comprising a flexible diaphragm disposed withinthe chamber to provide a non-sliding seal between the fixed wall and themovable wall of the chamber.
 23. A reel hub assembly comprising: a reelmotor having a motor shaft having a central axis and a central apertureextending axially therethrough; a generally cylindrical support memberdisposed concentrically about the central axis, the support member beingadapted to receive and support a plurality of shoes and permit onlyradial motion of the shoes with respect thereto, being connected infixed relationship with the motor shaft, and having a central apertureextending therethrough for receiving an actuator shaft; a plurality ofshoes, each being supported by the support member for only radial motionwith respect thereto; an actuator shaft disposed within the centralaperture of the support member and adapted for axial motion with respectto the support member, the actuator shaft having at least one concavityin the circumference thereof for receiving a plurality of drive links inmating relationship and having a central bore extending axiallytherethrough from a forward end rearwardly past the at least oneconcavity; a plurality of drive links, each extending between a shoe anda concavity in the actuator shaft to impart radial motion to a shoe inresponse to axial motion of the actuator shaft; a fixed wall disposed infixed relationship with the support member forward of the forward end ofthe actuator shaft to partially define a chamber which is incommunication with the axial bore in the actuator shaft at the forwardend thereof; a movable wall connected to the forward end of the actuatorshaft, the movable wall forming a part of the chamber and being operableto axially position the actuator shaft in response to fluid pressure inthe chamber; and means for defining a fluid path which couples arearward end of the axial bore through the actuator shaft to a source offluid having a controlled pressure.